原文地址：http://news.sciencenet.cn/htmlnews/2023/8/506474.shtm
Science, 11 AUG 2023, VOL 381, ISSUE 6658
《科學》2023年8月11日，第381卷，6658期
生態Ecology
Global water use efficiency saturation due to increased vapor pressure deficit
由于蒸汽壓差增加，全球水利用效率趨于飽和
▲ 作者：FEI LI, JINGFENG XIAO, JIQUAN CHEN, ASHLEY BALLANTYNE, KE JIN, BING LI, MICHAEL ABRAHA, AND RANJEET JOHN
▲ 鏈接：
https://www.science.org/doi/full/10.1126/science.adf5041
▲ 摘要：
在一個大氣中二氧化碳濃度不斷增加、氣溫不斷上升的世界里，植物如何在碳的增加和水的損失之間進行平衡的。作者研究表明，植物水分利用效率，即光合作用凈吸收碳與蒸騰氣孔導度之比，在1982~2000年間呈上升趨勢，但在2001~ 2016年間保持不變。
研究者解釋說，這是由于蒸氣壓增加和蒸發蒸騰加劇的結果。研究結果從另一個方面說明了氣候變暖的不利影響使實現碳中和變得更加困難。
▲ Abstract：
How have plants managed the trade‐off between carbon gain and water loss in a world of increasing atmospheric carbon dioxide concentrations and rising temperatures. Li et al. showed that plant water use efficiency, the ratio between the net assimilation of carbon through photosynthesis and the stomatal conductance of transpiration, increased from 1982 to 2000, but then remained constant from 2001 to 2016. The authors interpret this as being the result of increases in the vapor pressure and intensifying evapotranspiration. Their results illustrate one more way in which the adverse effects of climate warming make it more difficult to achieve carbon neutrality.
Declining cost of renewables and climate change curb the need for African hydropower expansion
可再生能源成本下降和氣候變化或抑制非洲水電擴張需求
▲ 作者：ANGELO CARLINO, MATTHIAS WILDEMEERSCH, CELRAY JAMES CHAWANDA, MATTEO GIULIANI, SEBASTIAN STERL, WIM THIERY, ANN VAN GRIENSVEN, AND ANDREA CASTELLETTI
▲ 鏈接：
hhttps://www.science.org/doi/full/10.1126/science.adf5848
▲ 摘要：
在人口增長和提高生活水平目標的推動下，特別是在最不發達區域，許多非洲國家計劃擴大其發電能力，以滿足未來能源需求。到2050年，非洲總電力需求預計將以每年5%到6%的速度增長，主要是在撒哈拉以南非洲地區。
然而，非洲能源系統的未來不僅受到額外能源需求的驅動，還將受到減緩和適應人為氣候變化的需要的驅動。水電是非洲電力系統的重要組成部分，特別是在撒哈拉以南國家。
它提供了總發電量的20%左右，但其全部潛力尚未被開發出來。傳統上被認為是低碳電力的廉價來源，整個非洲大陸正在考慮興建300多座水電站，相當于額外的100吉瓦發電能力。
▲ Abstract：
Driven by population growth and the goal of improving living standards, especially in the least-developed regions, many African countries plan to expand their power generation capacities to meet future energy demand. Indeed, total electricity demand is expected to grow by 5 to 6% per year until 2050, mainly in sub-Saharan Africa. Yet the future of African energy systems will not only be driven by the additional energy demand but also by the need to mitigate and adapt to anthropogenic climate change. Hydropower is an important component of African power systems, especially in sub-Saharan countries. It provides around 20% of total electricity generation, but its full potential has not been exploited yet. Traditionally considered a cheap source of low-carbon electricity, more than 300 hydropower plants, corresponding to an additional 100-GW power capacity, are under consideration across the continent.
物理學和生物物理學Physics & Biophysics
Wafer-scale δ waveguides for integrated two-dimensional photonics
集成二維光子學的晶圓尺度δ波導
▲ 作者：MYUNGJAE LEE, HANYU HONG, JAEHYUNG YU, FAUZIA MUJID, ANDREW YE, CE LIANG, AND JIWOONG PARK
▲ 鏈接：
https://www.science.org/doi/full/10.1126/science.adi2322
▲ 摘要：
芯片級光學電路需要在不斷減小的長度尺度和不同元件之間限制、控制和傳播光的能力。解決組件之間的光學不匹配通常會導致實際設備的尺寸和性能折衷。
作者研究表明，可以在超薄的二維材料（厚度<1納米）中限制和引導光。利用二硫化鉬單層，他們捕獲了一束激光，并產生了沿薄膜傳播厘米距離的二維光子波。通過集成微加工薄膜光學元件，研究者展示了各種光學功能，從而為二維納米光子學提供了一個通用平臺。
▲ Abstract：
Chip-scale optical circuits require the ability to confine, control, and propagate light over ever-decreasing length scales and across different components. Addressing the optical mismatch between components typically results in compromises in size and performance for practical devices. Lee et al. showed that they could confine and guide light in an ultrathin two-dimensional (2D) material (<1 nanometer thick). Using molybdenium disulfide monolayers, they trapped a laser beam and generated a 2D photonic wave propagating along the film over centimeter distances. By integrating microfabricated thin-film optical components, the authors demonstrated various optical functionalities, thereby providing a general platform for 2D nanophotonics.
Bioadhesive polymer semiconductors and transistors for intimate biointerfaces
用于親密生物界面的生物粘合劑聚合物半導體和晶體管
▲ 作者：NAN LI, YANG LI, ZHE CHENG, YOUDI LIU, YAHAO DAI, SEOUNGHUN KANG, SONGSONG LI, NAISONG SHAN, SHINYA WAI, AND SIHONG WANG
▲ 鏈接：
https://www.science.org/doi/full/10.1126/science.adg8758
▲ 摘要：
生物電子設備可用于監測或修復體內的重要組織，但這通常需要直接連接和粘附，當表面潮濕時，這是一個特別的挑戰。研究者設計了一種結合了生物粘合劑和半導體的雙網絡共聚物。
特別是刷子組件包括一個可以吸水的側組，在與組織表面的初始接觸時，它有助于干燥以增強附著力。研究者通過在離體大鼠心臟和活體大鼠肌肉上建立一個電生理記錄傳感器來證明新材料的能力。
▲ Abstract：
Bioelectronic devices can be used to monitor or repair vital tissues in the body, but this often requires direct interfacing and adhesion, which is a particular challenge when the surface is wet. Li et al. designed a double-network copolymer that combines a bioadhesive with a semiconductor. In particular, the brush component included a side group that could absorb water so that on initial contact with the tissue surface, it helps to dry it to enhance adhesion. The authors demonstrate the capabilities of their material by building a sensor for electrophysiological recording on an isolated rat heart and on in vivo rat muscles. —Marc S. Lavine
化學Chemistry
Chemical upcycling of polyethylene, polypropylene, and mixtures to high-value surfactants
聚乙烯、聚丙烯及混合物的回收，以獲得高價值表面活性劑
▲ 作者：ZHEN XU, NUWAYO ERIC MUNYANEZA, QIKUN ZHANG, MENGQI SUN, CARLOS POSADA, PAUL VENTURO, NICHOLAS A. RORRER, JOEL MISCALL, BOBBY G. SUMPTER , AND GUOLIANG LIU
▲ 鏈接：
https://www.science.org/doi/full/10.1126/science.adh0993
▲ 摘要：
將塑料廢物轉化為脂肪酸是補充這些高價值、大批量化學品來源的一種有吸引力的手段。研究者報道了將聚乙烯（PE）和聚丙烯（PP）以80%的轉化率轉化為脂肪酸的方法，其數平均摩爾質量分別高達~700和670道爾頓。該工藝適用于城市PE和PP廢物及其混合物。
溫度梯度熱解是PE和PP可控降解成蠟和抑制小分子生成的關鍵。蠟通過氧化硬脂酸錳和隨后的加工升級為脂肪酸。PP裂解比PE裂解可產生更多的烯烴蠟和更高的酸數脂肪酸。研究進一步將脂肪酸轉化為高價值、大市場容量的表面活性劑。工業規模的技術經濟分析表明，在不需要補貼的情況下，這一方法在經濟上是可行的。
▲ Abstract：
Conversion of plastic wastes to fatty acids is an attractive means to supplement the sourcing of these high-value, high-volume chemicals. We report a method for transforming polyethylene (PE) and polypropylene (PP) at ~80% conversion to fatty acids with number-average molar masses of up to ~700 and 670 daltons, respectively. The process is applicable to municipal PE and PP wastes and their mixtures. Temperature-gradient thermolysis is the key to controllably degrading PE and PP into waxes and inhibiting the production of small molecules. The waxes are upcycled to fatty acids by oxidation over manganese stearate and subsequent processing. PP?-scission produces more olefin wax and yields higher acid-number fatty acids than does PE?-scission. We further convert the fatty acids to high-value, large–market-volume surfactants. Industrial-scale technoeconomic analysis suggests economic viability without the need for subsidies.
Programming twist angle and strain profiles in 2D materials
二維材料的扭轉角和應變曲線編程
▲ 作者：MA?LLE KAPFER, BJARKE S. JESSEN, MEGAN E. EISELE, MATTHEW FU, DORTE R. DANIELSEN, THOMAS P. DARLINGTON, SAMUEL L. MOORE, NATHAN R. FINNEY, ARIANE MARCHESE, AND CORY R. DEAN
▲ 鏈接：
https://www.science.org/doi/full/10.1126/science.ade9995
▲ 摘要：
由單層材料在扭曲構型中堆疊而形成的莫爾維爾超晶格可以承載許多奇異態。然而，這種結構被發現是無序的，在單個樣品中扭曲角和應變的變化不可預測。研究者發現了一種控制扭轉角度和減少混亂的方法。
他們在六方氮化硼的頂部放置了帶狀石墨烯層，并使用原子力顯微鏡的尖端彎曲了帶的一端。由此產生的結構具有從緞帶開始彎曲到其末端不斷增加的扭曲角度，這種控制有望提高這類材料的可重復性以及對其的了解。
▲ Abstract：
Moiré superlattices formed by stacking single-layer materials in a twisted configuration can host many exotic states. However, such structures have been found to be disordered, with the twist angle and strain varying unpredictably within a single sample. Kapfer et al. found an elegant method for controlling the twist angle and decreasing the disorder. The researchers placed a ribbon-shaped graphene layer on top of hexagonal boron nitride and bent one end of the ribbon using the tip of an atomic force microscope. The resulting structure had a twist angle that increased continuously from the point at which the ribbon started bending to its end. Such control is expected to improve reproducibility and understanding of this class of materials.